Constitutional dynamic networks

The processes may be described by a constitutional dynamic network, consisting of a set of linked interconverting constituents that may undergo either agonistic or antagonistic variations (see below). 

Fig. 18 Graphical representation of a constitutional dynamic network of four interconnected and interconverting constituents AC, AD, BC, and BD...

Ulrich S, Lehn JM (2009) Adaptation and optical signal generation in a constitutional dynamic network. Chem Eur J 15 5640-5645... 

Fig. 19 Evolution of a constitutional dynamic system under the pressure of an effector E, leading to adaptation through generation of an enforced distribution (top). Graphical representation of the evolution of the corresponding dynamic network as a weighted square graph (bottom)...

The chemotactic response of Dictyostelium cells, and certainly also of other amoeboid cells such as neutrophils, is superimposed on the spontaneous dynamics of the cytoskeleton, in particular of the actin system in the cell cortex. This system consists basically of a network of bundled actin filaments, which are continuously turned over by polymerization and depolymerization. In Dicty-ostelium the polymerization rates of actin filaments constituting the network are in the order of 3 pm/s, corresponding to the... 

A set of applications simulating actual enterprise applications that will be connected to the Lplatform in order to constitute the network of applications required for the support of the Dynamic Manufacturing Network. Figure 6.9 gives an example with PDM systems of DMN members, and PLM collaborative platform constituting a PLM Hub (cPLM) ... 

Keywords Adaptation Constitutional dynamic chemistry Constitutional networks Dynamic materials Hydrogen bonding Imine formation Supramolecular chemistry... 

Fig. 12 Adaptive networks of constitutional dynamic polymers. Two-dimensional network representation of the effector-driven adaptation of the set of dynamers PI, P2, P3, and P4 in response to a chemical effector, the sodium cation Na" (see Fig. 11). The initial, close to statistical distribution of the four dynamers is strongly modified by addition of the cations, leading to an enforced distribution that displays a strong upregulation of P3, which binds Na, and the simultaneous increase of its agonist P4, whereas the antagonists P2 and P3 are strongly downregulated...

It is clear that, since the pitMieering work of Hermann Staudinger, the science and technology of polymer chemistiy has grown immensely, enriched by the work of innumerable research and engineering laboratories, and it will continue to do so. The present contributiOTi tries to paint one aspect of the full picture and to point to some fines of development. The incorporation of constitutional dynamics opens new perspectives. The analysis above may be extended to any set and network of dynamers, with more constituents, for which application of a given action will lead to a complex constitutional variation, resulting in a novel set of... 

The region from A to D is called the dynamic range. The regions 2 and 4 constitute the most imfwrtant difference with the hard delimiter transfer function in perceptron networks. These regions rather than the near-linear region 3 are most important since they assure the non-linear response properties of the network. It may... 

Besides the two most well-known cases, the local bifurcations of the saddle-node and Hopf type, biochemical systems may show a variety of transitions between qualitatively different dynamic behavior [13, 17, 293, 294, 297 301]. Transitions between different regimes, induced by variation of kinetic parameters, are usually depicted in a bifurcation diagram. Within the chemical literature, a substantial number of articles seek to identify the possible bifurcation of a chemical system. Two prominent frameworks are Chemical Reaction Network Theory (CRNT), developed mainly by M. Feinberg [79, 80], and Stoichiometric Network Analysis (SNA), developed by B. L. Clarke [81 83]. An analysis of the (local) bifurcations of metabolic networks, as determinants of the dynamic behavior of metabolic states, constitutes the main topic of Section VIII. In addition to the scenarios discussed above, more complicated quasiperiodic or chaotic dynamics is sometimes reported for models of metabolic pathways [302 304]. However, apart from few special cases, the possible relevance of such complicated dynamics is, at best, unclear. Quite on the contrary, at least for central metabolism, we observe a striking absence of complicated dynamic phenomena. To what extent this might be an inherent feature of (bio)chemical systems, or brought about by evolutionary adaption, will be briefly discussed in Section IX. 

Gels are obtained for concentrations shown in the temperature-concentration phase diagram (Figure 1). Electron spin resonance (ESR) shows (10) that for a given temperature only a fraction (p) of the initial steroid concentration is transferred from the solution to the gel network. The picture of this gel is thus of a supersaturation gel there is a dynamic equilibrium between free molecules in solution and aggregated steroid molecules included in the long objects which constitute the gel network. The free steroid molecules concentration at a temperature where the gel state is stable is (1-p), while C p is the steroid concentration within the solid-iike gel aggregates. 

Reaction-induced phase separation is certainly also the reason for which an inhomogeneous structure is observed for photocured polyurethane acrylate networks based on polypropylene oxide (Barbeau et al., 1999). TEM analysis demonstrates the presence of inhomogeneities on the length scale of 10-200 nm, mostly constituted by clusters of small hard units (the diacrylated diisocyanate) connected by polyacrylate chains. In addition, a suborganization of the reacted diisocyanate hard segments inside the polyurethane acrylate matrix is revealed by SAXS measurements. Post-reaction increases the crosslink density inside the hard domains. The bimodal shape of the dynamic mechanical relaxation spectra corroborates the presence of a two-phase structure. 

Process-scale models represent the behavior of reaction, separation and mass, heat, and momentum transfer at the process flowsheet level, or for a network of process flowsheets. Whether based on first-principles or empirical relations, the model equations for these systems typically consist of conservation laws (based on mass, heat, and momentum), physical and chemical equilibrium among species and phases, and additional constitutive equations that describe the rates of chemical transformation or transport of mass and energy. These process models are often represented by a collection of individual unit models (the so-called unit operations) that usually correspond to major pieces of process equipment, which, in turn, are captured by device-level models. These unit models are assembled within a process flowsheet that describes the interaction of equipment either for steady state or dynamic behavior. As a result, models can be described by algebraic or differential equations. As illustrated in Figure 3 for a PEFC-base power plant, steady-state process flowsheets are usually described by lumped parameter models described by algebraic equations. Similarly, dynamic process flowsheets are described by lumped parameter models comprising differential-algebraic equations. Models that deal with spatially distributed models are frequently considered at the device... 

The molecular dynamics simulation indicated that, unlike polarization (which oscillates), the disruption of hydrogen bonding varies smoothly in the vicinity of the surface and constitutes therefore a better choice as an order parameter. There were a number of computational approaches13 14 16 and lattice model calculations17 which related the hydration force to the disruption of the hydrogen bonding networks when two surfaces approach each other. 

Barboiu M (2010) Dynamic interactive systems dynamic selection in hybrid organic-inorganic constitutional networks. Chem Commun (Camb) 46 7466-7476... 

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